Usually disc 1 will be a "play" disc, or they will be labeled (or the manual will say, surely).

I just know that a lot of times a corrupt install (especially if your computer locked up during an installation process) can be fixed by Your Uninstaller. I know it was that way with Quake3 engine games like Jedi Academy.

If all else fails, try the official site's tech support (Yoda's Help Desk)... though Aspyr Media has a page that might be useful as well. The patches are supposed to fix mostly performance issues.